Hydraulic press for compacting metal powder

ABSTRACT

A hydraulic metallic powder press including a press cylinder and a piston displaceable in the press cylinder. A piston rod is connected to the piston and a seal positioned adjacent the piston rod and at a location where the piston is led out of the press cylinder. A free end of the rod bears a die and is adapted to be introduced into a cavity for compacting metallic powder contained therein. An adjustable sleeve is provided in the press cylinder inwardly of the seal. The sleeve at least partially encloses the piston rod and has an external thread and the press cylinder has an internal thread in mating relationship with the sleeve thread. The sleeve further has a slide. A rotatable gland at least partially encloses the sleeve and has a longitudinal groove therein for guiding the slide. The groove runs in the axial direction of the piston rod and a drive motor is operatively coupled for rotatably moving the gland. Accordingly, the length of the stroke of the die into the cavity is thereby limited.

United States Patent Ginzel et al.

1 Nov. 13, 1973 1 HYDRAULIC PRESS FOR COMPACTING METAL POWDER [75]lnventors: Severin Ginzel; Peter Niederhuber,

both of Munich, Germany [73] Assignee: W. Bussmann KG, Munich, 1 Germany[22] Filed: Aug. 8, 1972 1 ppl 032 8178 i N [30] Foreign ApplicationPriority Data Apr. 24, 1969 Germany P Related U.S. Application Data [63]Continuation-impart of Ser. No. 28,341, April 14,

1970, abandoned.

[52] U.S. Cl 425/78, 92/l3.1, 100/256, 100/257, 72/441 [51] Int. Cl B2213/04 [58] Field of Search 425/78, 151, 363; 72/441, 453; 100/256, 257;92/131 [56] References Cited UNITED STATES PATENTS 2,648,096 8/1953Baigent 92/l3.l X 2,762,078 9/1956 3,044,138 7/1962 3,080,852 3/19633,191,232 6/1965 Haller 425/7 Primary Examiner-Robert L. Spicer, Jr.Att0rney.lim W. Gipple et a1.

[57] ABSTRACT A hydraulic metallic powder press including a presscylinder and a piston displaceable in the press cylinder. A piston rodis connected to the piston and a seal positioned adjacent the piston rodand at a location where the piston is led out of the press cylinder. Afree end of the rod bears a die and is adapted to be introduced into acavity for compacting metallic powder contained therein. An adjustablesleeve is provided in the press cylinder inwardly of the seal. Thesleeve at least partially encloses the piston rod and has an externalthread and the press cylinder has an internal thread in matingrelationship with the sleeve thread. The sleeve further has a slide. Arotatable gland at least partially encloses the sleeve and has alongitudi' nal groove therein for guiding the slide. The groove runs inthe axial direction of the piston rod and a drive motor is operativelycoupled for rotatably moving the gland. Accordingly, the length of thestroke of the die into the cavity is thereby limited.

5 Claims, 3 Drawing Figures EESERW/R PATENTEUNHYIIJIQIS I 377L930 sum 1or 3 Fig.1

FESER V011? PATENTEUNBY 1a 1925 3771, 930

SHEET 2 0F 3 v HYDRAULIC PRESS FOR COMPACTING METAL POWDER RELATED U.S.APPLICATION This is a continuation-in-part application of Ser. No.28,341, now abandoned filed Apr. 14, 1970 by Severin Ginzel et al. forHydraulic Press for Compacting Metal Powder.

The present invention is concerned with a hydraulic metal powder pressin which a press cylinder has been placed within a machine frame. In thepress cylinder, a piston on which a pressure medium acts is guided insuch a way that it can be moved to and fro. The piston has a piston rodwhich leads tightly out of the cylinder, and the free end of whichsupports a pressing table or pressing plate, to which a press die hasbeen attached. The press die is shaped in accordance with the form ofthe pressing to be manufactured and is introduced into a shaping cavityof a pressing tool which is filled with metal powder, when the pistonrod is extended, so that the metal powder will be compacted to apressing, under high pressure.

The precision of the dimensions of pressings manufactured in this waydepends on how precisely the stroke of the piston supporting the pressdie can be circumscribed during the pressing process. In a knownhydraulic metal powder press, the height of lift is circumscribed byadjustable stops that are arranged within the machine frame. The stopshave been mounted on supporting columns and their position can beadjusted very finely by way of worn gears. But, this has thedisadvantage that dust, in particular metal dust, collects on the stops,whereby the precision of the stroke limitation of the piston willsuffer, unless the stops are carefully kept clean at all times.

A sheet-metal press is also known, in which the stroke limitation of thepiston is achieved by means of stop rings which lie within the presscylinder, and which can be screwed, from the outside, into the presscylinder far (Swedish Pat. No. 204,205). The adjustment of those stoprings takes place by means of a snail and of a worm gear that is joinedrigidly with the stop rings. In order to maintain the snail and wormgear in such a position that they engage one another, when the stoprings are displaced into the press cylinder or out of it, the

The figures of the drawings show the following:

FIG. 1 is a schematic longitudinal section through an upper presscylinder of a hydraulic metal powder press in accordance with theinvention;

FIG. 2 is a sectional view from above of a pressing table, taken alongthe line 22- in FIG. 3, and

FIG. 3 is a lateral view of. the upper press cylinder and of the partsmounted underneath it, in accordance with the present invention, asviewed from the same direction as the longitudinal section in accordancewith FIG. 1.

As is evident from FIG. 2, a geared electric engine 1 drives, by way ofa driving shaft, a snail 2 which mates with a worm gear 3. The worm gear3 is connected in such a way that it will rotate a rotatable gland 5that is pivoting in a cylinder bottom 4 of a press cylinder 9 (FIG. 1).The inside of the rotatable gland 5 has an axial longitudinal groove 21in which a slide 6 is guided, which is attached to the lower part of astop-sleeve 7. The stop'sleeve 7 has been designed in one part forsmaller presses, but for larger presses, it has been designed in twoparts, as shown here. The division in two parts has the advantage that ashaft packing 8 can be inserted at the joint between the two parts ofthe stop sleeve 7.

The upper part of the stop-sleeve 7 has been screwed into acorresponding thread of the press cylinder 9, by means vof a buttressthread 22, and its height can be modified by turning the stop-sleeve 7.g

The shaft supporting the snail continues as a worm shaft 11 for anadditional snail 12, which mates with an additional worm gear 13 (FIG.2). The additional worm gear 13 is joined in such a way that it willrotate a wormgear spindle 14, as may be seen in FIG. 3, and rotates itwhen the engine 1 is running. The worm-gear spindle 14 is supported bybearings 14a and 14b, which are mounted on the press cylinder 9, so thatit can rotate. A micro-limit switch 15 is screwed on the wormsnail hasto be supported in such a way that it may be shifted at a right angle toits longitudinal axis. This support that can be shifted, and thecorresponding design of the snail are complicated.

his the purpose of this invention to design a hydraulic metal powderpress, in such a way that the height of lift of the piston can becircumscribed as precisely as possible, without constant supervision.

Another purpose of this invention consists in the creation of ahydraulic metal powder press with a stroke limit for the press plunger,in which the stop constituting the limit supports a worm gear which canbe driven by a snail placed in the machine frame, so as to bestationary. A further aim of the invention is to create a hydraulicmetal powder press with a stroke limit for the press plunger, by meansof which the press plunger is supported evenly and symmetrically withinthe frame of the machine. Further purposes and characteristics of thepresent invention will become apparent from the following description ofa preferred example of its design, on the basis of the encloseddrawings, and from the claims.

gear spindle 14 by means of a threaded sleeve, details of which have notbeen shown, and is prevented from rotating as is evident from FIG. 3 bymeans of a projection 18 which protrudes inside between two parallelrods (18a) mounted at a distance from one another. Only one of the tworods 18a, which are also joined rigidly to the press cylinder 9, can beseen in FIG. 3. In the press cylinder 9, a piston 9a has been mounted insuch a way that it may slide and be moved; it has a piston rod 9b. Thepiston rod 9b passes through the stop-sleeve 7 and its free end supportsa pressing table 22. Seal 28 is positioned adjacent piston rod 9b at thelocation where piston rod 9b is led out of press cylinder 9. As may beseen from FIG. 3, a sliding bar 16 is rigidly attached to the pressingtable 22 (e.g. screwed to it). This sliding bar 16 freely penetratesthrough an opening 23 of a base plate 24, in which the bearing 14b ofthe worm-gear spindle 14 has been mounted. To the press cylinder 9, asleeve 25 has been attached, through which the sliding rod 16 alsoprojects, and in which it is guided in such a waythat it is parallel tothe worm-gear spindle 14. A stop pin 17 has been fastened to the slidingrod 16; the path of motion of the stop pin 17 agrees with the path ofmotion of the micro-limit switch 15 so that it may meet it during anapproach. The distance between the stop pin 17 and the micro-limitswtich 15 is adjusted before the start of the operation of the hydraulicmetal powder press in such a way that it is equal to the distancebetween the lower surface of the piston 9a and the upper stop face ofthe stop-sleeve 7.

On the engine frame, limit switches 19 and 20, which lie on top of oneanother in the path of motion of the projection 18, have been mounted;normally, they are closed.

As is evident from FIG. 1, an inlet opening a for the pressure mediumhas been provided at the upper end of the press cylinder 9, above theupper surface of the piston 9a. Below the bottom surface of the piston9a, an outlet opening 10b has been made in the press cylinder 9; it islinked with an outlet duct 10c which is shown by a schematic drawingonly and which leads to a reservoir R for the pressure medium; thereservoir is also drawn schematically only. In the outlet duct 100, anelectromagnetic control valve V has been inserted, which is closed whenthe piston 9a is not moved, or when the stop-sleeve 7 as will beexplained in detail later is not shifted. The electromagnetic controlvalve V is connected with electric supply lines of the engine 1, in sucha way that its magnet is excited simultaneously with the swtiching on ofthe engine 1 by means of a switch S (FIG. 1). In the example of thedesign of the invention described, the pressure medium in the outletduct 100 is under the same pressure that prevails also in the reservoirR. This pressure may be atmospheric pressure. But, it is also possibleto use the duct 10c as a supply duct for a pressure medium underpressure, that is fed by a pump which has not been shown so as to bringback the piston 9a from its lower position once more into the upperoriginal position as shown in FIG. 1. In this case, an additional valvewhich has not been shown may be inserted into the duct 10c; this valveestablishes, during the return movement of the piston 9a, a connectionwith the pump which has not been shown.

When the stop-sleeve 7 is moved, the operation progresses as follows:When the switch S (FIGS. 1 and 2) is closed, the electromotor 1 issupplied with current and starts. In consequence thereof, the snails 2and 12 will turn and rotate the associated worm gears 3 and 13,respectively. Due to the rotation of the worm gear 3, the rotatablegland 5 with the groove 21 will also rotate and, thereby, actuate inaddition the stopsleeve 7 by way of the slide 6. Depending on the senseof rotation of the engine 1, the stop-sleeve 7 will be screwed by meansof the thread 22 further into the press cylinder 9, or out of it. Inthat way, the position of its upper stop face changes, and thereby, thedistance between that stop face and the bottom surface of the piston 9aalso changes. Since the slide 6 can-slide axially in the slot 21 of thepacking box 5, the adjustment'of the stop-sleeve 7 will not be impeded.

By means of the rotation of the worm gear 13, which takes place at thesame time, the worm-gear spindle 14 is rotated, so that the micro-limitswitch 15 which is kept from rotating by the projection 18 and the rods18a, will be moved axially at the same speed as the stop-sleeve 7.Accordingly, its distance from the stop pin 17 changes by the sameamount as thedistance between the bottom surface of the piston 9a andthe upper stop face of the stop-sleeve 7.

Simultaneously with the closure of the switch S and with the start ofthe engine 1 which results therefrom, the magnet of the magnetic valve Vis excited, so that it will open. In this way, it is possible, when thestopsleeve 7 is adjusted, by way of the duct 10c to expel the pressuremedium out of the press cylinder 9 or to suck it into the press cylinder9. It is evident from the circuit that the magnetic valve will remainopen as long as the motor 1 is running, and the stop-sleeve 7 and themicro-limit switch 15 are moved thereby. When the switch S is reopened,the engine 1 comes to a stop, and the adjustment motion of thestop-sleeve 7 and of the micro-limit switch 15 is interrupted. Inaddition, the magnetic valve V closes again.

Once the stop-sleeve 7 has been moved into the desired position in themanner discussed in the preceding paragraphs, the piston 9a can beloaded with the pressure medium. To that end, the pressure medium isintroduced into the press cylinder by way of the inlet opening 10a,while the magnetic valve V is opened at the same time. The pertinentcircuit for the introduction of the pressure medium and for the openingof the magnetic valve V in the outlet duct 10c is well known and doesnot require any further explanation at this point. Due to the loadingwith the pressure medium, the piston 9a moves downward from the originalposition as shown in FIG. 1. In that way, the slide rod 16 which isfastened to the pressing table 22, slides within the aperture 23 andwithin the sleeve 25, and moves the stop pin 17 toward the micro-limitswitch 15. When the bottom surface of the piston 9a reaches the upperstop face of the stop-sleeve 7, the movement of the piston 9a isarrested. At the same time, the stop pin 17 reaches the micro-limitswitch 15 and causes thereby the lighting of a control lamp, which hasnot been shown. An operator will, therefore, be able to see that themotion of the piston 9a has been arrested. The limit switches 19 and 20,which interact with the projection 18 of the micro-limit switch 15, havebeen inserted into the circuit of the electro-motor l, in such a waythat they break that circuit when they are run by the projection 18. Inthat way, it is made impossible that, during the movement of thestop-sleeve 7, the slide 6 leaves the groove 21 in an upward or downwarddirection. Therefore, the distance between the two limit switches 19 and20 corresponds to the length of the groove 21.

We claim: 1

1. A hydraulic metallic powder press comprising a press cylinder, apiston displaceable in the press cylinder, a piston rod connected to thepiston, a seal positioned adjacent said piston rod and ata locationwhere the piston is led out of the press cylinder, a free end of the rodbeing positioned outside of the press cylinder and being attached to adie which is adapted to be in- I troduced into a cavity for compactingmetallic powder contained therein, an adjustable sleeve provided in thepress cylinder inwardly of said seal, said sleeve at least partiallyenclosing the piston rod and having an external thread, said presscylinder having an internal thread in mating relationship with saidsleeve thread, the sleeve further having a slide, a rotatable gland atleast partially enclosing said sleeve and having a longitudinal groovetherein for guiding said slide, said groove running in the axialdirection of the piston rod, a drive motor operatively coupled to saidgland for rotatably moving said gland whereby said adjustable sleeve ismoved axially and the length of the stroke of the die into the cavity isvaried, and means for introducing and for causing the movement of saiddie.

2. An hydraulic metallic powder press as in claim 1, further comprisinga spindle mounted adjacent to and outside of the press cylinder, saiddrive motor coupled to said spindle to rotate said spindle, a firstlimit switch mounted on said spindle for indicating when said pistoncontacts said sleeve, so as to move axially along said spindle when saidspindle is rotated and by the same axial amount as said sleeve, a sliderod mounted for movement with the piston rod, said slide rod beingdisposed outside the cylinder and displaceable parallel to the pistonrod, and a stop pin mounted on said slide rod and positioned in the pathof movement of said first limit switch so that said first limit switchis actuated when said piston contacts said sleeve.

3. An hydraulic metallic powder press as in claim 1,

in which the external thread on the sleeve and the internal thread ofthe press cylinder are buttress threads.

4. An hydraulic metallic powder press as in claim 2, further includingsecond and third limit switches for stopping said drive motor when saidsleeve has been moved axially a predetermined distance and a cam mountedon said first switch to actuate said second and third limit switcheswhen said sleeve has been moved axially a predetermined distance.

5. An hydraulic metallic powder press as in claim 1 in which the meansfor introducing and removing a pressure medium from the pressurecylinder include valve means.

1. A hydraulic metallic powder press comprising a press cylinder, apiston displaceable in the press cylinder, a piston rod connected to thepiston, a seal positioned adjacent said piston rod and at a locationwhere the piston is led out of the press cylinder, a free end of the rodbeing positioned outside of the press cylinder and being attached to adie which is adapted to be introduced into a cavity for compactingmetallic powder contained therein, an adjustable sleeve provided in thepress cylinder inwardly of said seal, said sleeve at least partiallyenclosing the piston rod and having an external thread, said presscylinder having an internal thread in mating relationship with saidsleeve thread, the sleeve further having a slide, a rotatable gland atleast partially enclosing said sleeve and having a longitudinal groovetherein for guiding said slide, said groove running in the axialdirection of the piston rod, a drive motor operatively coupled to saidgland for rotatably moving said gland whereby said adjustable sleeve ismoved axially and the length of the stroke of the die into the cavity isvaried, and means for introducing and removing a pressure medium fromsaid press cylinder for causing the movement of said die.
 2. Anhydraulic metallic powder press as in claim 1, further comprising aspindle mounted adjacent to and outside of the press cylinder, saiddrive motor coupled to said spindle to rotate said spindle, a firstlimit switch mounted on said spindle for indicating when said pistoncontacts said sleeve, so as to move axially along said spindle when saidspindle is rotated and by the same axial amount as said sleeve, a sliderod mounted for movement with the piston rod, said slide rod beingdisposed outside the cylinder and displaceable parallel to the pistonrod, and a stop pin mounted on said slide rod and positioned in the pathof movement of said first limit switch so that said first limit switchis actuated when said piston contacts said sleeve.
 3. An hydraulicmetallic powder press as in claim 1, in which the external thread on thesleeve and the internal thread of the press cylinder are buttressthreads.
 4. An hydraulic metallic powder press as in claim 2, furtherincluding second and third limit switches for stopping said drive motorwhen said sleeve has been moved axially a predetermined distance and acam mounted on said first switch to actuate said second and third limitswitches when said sleeve has been moved axially a predetermineddistance.
 5. An hydraulic metallic powder press as in claim 1 in whichthe means for introducing and removing a pressure medium from thepressure cylinder include valve means.